Ship&#39;s propeller mounting



Oct. 15, 1968 c. w. HERBERT SHIP'S PROPELLER MOUNTING Filed Feb. 21, 1967 a a on mm y. H k mm mm i a \8 United States Patent 3,405,765 SHIPS PROPELLER MOUNTING Colin Wray Herbert, Marske-by-the-Sea, England, assignor to The Glacier Metal Company Limited, Middlesex, England Filed Feb. 21, 1967, Ser. No. 617,540 Claims priority, application Great Britain, Feb. 22, 1966, ,827/ 66 9 Claims. (Cl. 170173) ABSTRACT OF THE DISCLOSURE A marine propeller mounting in which the propeller has integral fixed blades on a hollow cylindrical boss with an internal integral flange disposed centrally under the roots of the blades and the flange of the boss is bolted to a radially-extending end flange on the shaft whereby the overhang of the weight of the propeller with respect to the shaft bearing is minimized.

The present invention relates to the mounting of ships propellers.

In conventional mountings the propeller boss is commonly fitted over the tapered end of the propeller shaft and secured by a nut. It is also known to attach a boss directly to an end flange on the propeller shaft.

The first of these mounting arrangements has a history of failure as evidenced by the records of classification societies throughout the world. In addition with either of these mounting arrangements the whole of the propeller necessarily lies considerably aft of the stern hearing supporting the propeller shaft and of the outboard rotary seal surrounding the shaft. The weight of the propeller thus imposes a heavy load on the bearing and exerts a large bending moment on the propeller shaft. The natural frequency of whirling of the assembly is primarily influenced by the axial distance between the center of gravity of the propeller and the assessed center of the stern tube bearing and thus it is desirable to minimise this distance both from the whirling and propeller weight point of view.

In accordance with the present invention there is provided a propeller and shaft assembly for ships in which the propeller shaft has a radial flange, and the propeller boss is a hollow cylinder with an internal flange between the ends thereof attached to the shaft flange, the cylindrical wall of the boss overhanging the shaft flange on the inboard side.

The internal flange may be arranged so that a mid chord plane of a root of the propeller blade passes through or near the flange whereby material continuity is obtained of the blade root through the hollow cylinder of the propeller boss and into the internal flange,

With the hollow cylindrical propeller boss and its internal flange it is possible to secure the propeller to the shaft with fixing means accessible from the aft end of the propeller so that the flanged mounted propeller may be removed without disturbing the shaft.

The forward face of the shaft flange can carry a shaft carrier bush designed to fit within a bearing ring on the stern frame to support the propeller shaft during inspection when the main bearing is removed. The shaft carrier bush can also carry a gland liner for engagement by stationary sealing rings to form the outboard rotary seal.

In such a propeller and shaft assembly it is possible for the shaft carrier bush and outboard rotary seal to lie wholly or partly within the propeller boss thereby reducing the distance between the axial center of gravity of the propeller and the axial position of the support center of the stern hearing. In a preferred construction 3,405,765 Patented Oct. 15, 1968 'ice part of the stern frame of the ship projects into the propeller boss.

To reduce further the adverse effects of the weight of the propeller a buoyancy chamber can be fitted to the aft end of the propeller boss to provide a lifting moment acting in opposition to the weight of the propeller. The buoyancy chamber is preferably a closed hollow shell, which may be made of synthetic plastics material reinforced with glass fibre, filled with a body of foam material having preferably a closed cell structure.

The invention will now be described in more detail with the aid of an example illustrated in the accompanying drawing, which shows a longitudinal section of a propeller and shaft assembly in accordance with the invention.

A propeller shaft 10 is supported at its aft end by a stern bush 11 containing a plain bearing or a ball or roller race hearing. The stern bush 11 is supported at its aft end by a stern frame 12. The shaft 10 has a radial flange 13 at its aft end and an internal flange 14 of a hollow cylindrical propeller boss 15 is attached to the flange 13 by bolts 16 secured by hydraulically-tightened nuts 17. The periphery of the flange 13 is tapered at 18 which assists when fitting the propeller to the shaft. There is a small clearance between the outside diameter of the flange 13 and the inner wall of the boss 15. The shaft 10 has an annular projection 19 which extends into the central opening 20 within the flange 14 to further assist location of the propeller boss during mounting.

The forward face of the shaft flange 13 carries a shaft carrier bush 21 with a groove 22 in its forward face. The inner wall of the groove 22 fits freely within a bearing ring 23 which is mounted in an extension 12a of the stern frame. A sealing ring 24 fits freely within the outer wall of the groove 22. When the propeller shaft 10 is moved forward the inner wall of the groove 22 seats in the bearing ring 23 and the shaft 10 is thus supported, enabling the stern bush 11 to be withdrawn for inspection of the bearing surfaces. At the same time the ring 24 engages the outer wall of the groove 22 and provides a water-tight seal to replace the outboard rotary seal the static part of which formed by a gland liner 25 is withdrawn forward with the bearing assembly for inspection and maintenance, leaving the rotating part 26 attached to the shaft carrier bush 21.

The extension 12a of the stern frame lies within the propeller boss 15 and the wall of the boss extends close to and flush with the outer surface of the stern frame 12. There is thus no necessity for a rope guard, the outboard seal assembly and other parts being protected by the stern frame and the propeller boss. The rotary seal 25, 26 is itself within the length of the propeller boss 15.

A diaphragm 27 is fitted in the aft end of the propeller boss 15 to seal the interior of the boss and the end of the shaft 10 against ingress of sea water. Mounted on the aft end of the boss 15 is a buoyancy chamber consisting of a closed hollow shell 28 made of synthetic resin reinforced with glass fibre and filled with a body 29 of foam plastic with a closed cell structure. The shell 28 has strengthening metal inserts 30 and is attached to the propeller boss 15 by bolts 31. The shell 28 is of generally cylindrical form with a slightly convex tapering surface continuing the outline of the propeller boss.

I claim: 7

1. A propeller and shaft assembly for ships comprising a propeller shaft, a radial flange on the propeller shaft, and a propeller comprising a hollow cylindrical boss and a plurality of blades, the boss having an integral flange extending inwardly and attached to the radial flange of the shaft, wherein the blades are integral with the boss, the flange is located within the boss centrally under the roots of the blades, the shaft flange is located within the boss and the boss overhanging the radial flange of the shaft on the inboard side.

2. An assembly as claimed in claim 1 wherein the shaft flange has a periphery tapering towards its aft end and the inner face of the boss is similarly shaped to facilitate reassembly.

3. An assembly as claimed in claim 1 in Which said internal flange bounds a central aperture and the shaft has an annular projection extending into the central aperture to assist in locating the boss with respect to the shaft.

4. An assembly as claimed in claim 1 including fixing means securing said flanges together, said fixing means being accessible from the aft end of the propeller whereby the propeller may be removed without disturbing the shaft.

5. An assembly as claimed in claim 1 including a stern frame having a bearing ring, and a shaft carrier bush mounted on the forward face of the shaft flange, said shaft carrier bush being constructed for co-operation with said bearing ring to support the shaft for inspection and maintenance.

6. An assembly as claimed in claim 5 including a gland liner mounted on the shaft carrier bush and stationary sealing rings engaging said gland liner to form an outboard rotary seal for the shaft.

7. As assembly as claimed in claim 1 including a stern frame portion disposed within the forward end of the boss.

8. An assembly as claimed in claim 1 including a buoyancy chamber attached to the aft end of the propeller boss.

9. An assembly as claimed in claim 8 wherein the buoyancy chamber is a closed hollow shell enclosing a body of rigid foam material.

References Cited UNITED STATES PATENTS 2,581,834 1/1952 Brown. 3,228,482 1/1966 Bunyan.

794,932 7 1905 Fullerton. 2,028,448 1/ 1936 Harza -16023 X 2,514,097 7/1950 Sharp 170-16023 2,933,141 4/1960 Kapsenberg 170-16023 2,987,123 6/1961 Liaaen 170-16023 FOREIGN PATENTS 679,926 8/1939 Germany.

178,739 3/1962 Sweden.

997,656 10/ 1949 France.

EVERETTE A. POWELL, 111., Primary Examiner 

